1. Field of the Invention
The invention relates to metallurgy and more particularly to withdrawal roll units of continuous metal casting machines.
The present invention can find an effective application in horizontal continuous metal casting machines, especially in those continuous casting machines where ingots are withdrawn from moulds and simultaneously rotated about their own axes.
2. Description of the Prior Art
Horizontal continuous casting machines are currently finding an extensive use for casting ferrous and nonferrous metals and alloys. These machines present a number of substantial advantages as compared to existing types of continuous metal casting machines (small height of column of molten metal in the machine which greatly simplifies the design of the machine, lesser requirements in metal for manufacturing the machine, no open meniscus of molten metal in mould, simple operation).
Easy operation of continuous casting machines, their reliability and stability of operation, excellent quality of cast ingots and the cost of the machine as a whole are greatly dependent upon the design of one of the main mechanisms of the machine--the withdrawal roll unit.
There are known withdrawal roll units comprising withdrawal rolls secured to oscillating levers mounted on a rotating cage.
U.S. Pat. No. 1,269,929 (France), cl. B 22 d, describes a withdrawal roll unit, wherein two withdrawal rolls are secured to oscillating levers, and the levers, in their turn, to a rotating cage, parallelly to the axis thereof and, therefore, parallelly to the process axis of the machine. The withdrawal rolls and the cage are rotated through a system of spur and bevel gears.
A material disadvantage of this type of withdrawal roll unit is the location of the oscillating levers with secured thereto withdrawal rolls longitudinally of the process axis of the machine. The longitudinal location of the oscillating levers, first, increases the dimensions of the machine longitudinally of the process line, this making the whole of the process line longer; second, such an arrangement of the oscillating levers complicates the design of the withdrawal roll drive. The design of the withdrawal roll unit admits of not more than two withdrawal rolls, so that the pressure the rolls exert upon an ingot being cast to ensure the withdrawal thereof from a mould may be so great as to mar the quality of the ingot surface.